Method and material for surface brightening layers containing gelatin as the binding agent using anionic water-soluble diaminostilbene fluorescent compounds



United States Patent 3,269,840 METHOD AND MATERIAL FOR SURFACE BRIGHTENING LAYERS CONTAINING GEL- ATlN AS THE BINDING AGENT USING ANI- ONIC WATER-SOLUBLE DIAMINOSTILBENE FLUORESCENT COMPOUNDS Hendrik Adolf Pattyn and Willem Karel Koerber, both of Wilrijk-Antwerp, Belgium, assignors to Gevaert Photo- Producten N.V., Mortsel-Antwerp, Belgium, a Belgian company No Drawing. Filed Mar. 27, 1964, Ser. No. 355,446 Claims priority, application Great Britain, May 19, B59, 16,820/59 17 Claims. (Cl. 9682) The present application is a continuation-in-part of our US. patent application Serial No. 29,562, now abandoned.

The present invention relates to a process for brightening the white surface of papers provided with one or more surface coatings composed of materials which are not able to bind securely optical brightening agents, and more particularly relates to a process for brightening the white areas in photographic images by means of such agents whilst bleeding of the brightening agents from the photographic layers is inhibited.

In the US. patent application Serial No. 739,211, filed June 2, 1958, now US. Patent No. 3,047,390, is claimed a method of brightening the surface of a paper having at least one surface-coating containing a White pigment, wherein a water-insoluble macromolecular product, to which a substantially colorless blue-fluorescinig ultra-violet absorbing compound hereinafter referred to as orighb ening agent is bound, is added to or incorporated into the pigment surface-coating material and/ or the material forming at least one superposed coating.

According to preferred embodiments of the method according to the said co-pending application by which the rinsing or bleeding of the brightening agents out of the layers to which they were added is completely inhibited, finely divided Water-insoluble macromolecular products having a low degree of polymerization are treated with a solution or dispersion of a brightening agent which possesses a pronounced substantivity in respect of the macromolecular prod-net used, and after filtration, the fluorescent mass obtained is added to the material which is to form one or more covering layers on the paper support. As macromolecular products which in finely divided states are suitable for carrying out this method can be mentioned in particular: cellulose, polyesters, pol-yanmides and urea-formaldehyde resins.

If the water-insoluble macromolecular products employed are carefully chosen, very favorable results are obtainable by the method according to the aforesaid pending application. In some cases, however, certain difiiculties are involved in bringing macromolecular products into a finely divided state. These difficulties can be avoided for the greater part at least by applying the invention the subject of the US. patent application Serial No. 14,200, filed March 11, 1960, now abandoned, wherein the water-insoluble macromolecular product used is in the form of an emulsion polylmer.

Now we have found that by using an anionic fluorescent compound in conjunction with one or more of certain water-soluble polymers not only an intense fluorescence is caused and a :greater increase of brightness is attainable than is obtained when using the anionic fluorescent compound alone in optimum concentration, but the gain of fluorescence is also maintained during the processing by the fact that the fluorescent substance is bound to the Water-soluble polymer in a kind of addition compound, thus making the fluorescent compound fast to diffusion, provided that the molecular weight of the polymer and/or the degree of hardening applied to the layer containing the polymer are appropriately selected.

Thus the invention is of particular value as applied to the manufacture of photographic materials which are to be processed in wet state viz in the conventional aqueous processing \baths and which are to be viewed by reflection. It may, however, be applied to all kinds of paper materials; e.g. the surface of a paper having at least one surface-coating containing a white pigment, can be brightened by adding to or incorporating into at least one layer of the group consisting of the surfacecoating which contains the white pigment and at least one superposed coating, an aqueous solution of an optical brightening agent and a water-soluble vinyl polymer as herein after defined.

As anionic fluorescent compounds which are suitable for applying the method of our present invention we would particularly mention compounds of the class represented by the following general formula:

Q,NH NH-Q Z O H=CH R1 R1 wherein: Q: (a)

N n F wherein R and R (the same or different) each represent a hydrogen atom; a halogen atom e.g. chlorine or bromine; a hydroxyl group; an aryloxy group e. g. phenoxy, o-toloxy or p-sulphophenoxy; an alkoxy group e.g. methoXy or ethoxy; a heterocyclic radical e.g. morpholinyl, piperidyl or furfuryl; -a thioalkyl group e.g. thiomethyl or thioethyl; a thioaryl group e.g. thiophenyl or thiotolyl; a thioheterocyclic group e.g. thiobenzothiazyl; an amino group; an alkylamino group either substituted or not e.g. methylamino, ethyla-mino, propylamino, dimethylamino, diethylamino, dodecyclamino, cyclohexylamino, beta-hydroxyethylamino, di(bet1a hydroxyethyl) amino, betasulphoethylamino or an arylalmino group e.g. anilino, 0-, mand p-sulphoanilino, o-, pand p-chloro-anilino, o-, mand p-anysilamino, o-, mand p-toluidino, o-, mand p-carboxy-anilino, hydroxyanilino, sulphnaphthylamino, o-, mand p-amino-anilino, or p-acetamido-anilino; or (b) R CO, wherein R represents an atom, group or radical within the above definition of R and R Q'=( it. wherein R and R each represents an atom, group or radical within the definition of R and R in the above (a) definition of Q or (b) R -CO, wherein R represents an atom, group or radical within the definition of R and R in the above (a) definition of Q; R; and R each represents a water-solubilizing group e.g. a sulpho group or a carboxyl group or salts formed by said groups, e.g. amine salts, alkali metal salts or alkaline earth metal salts e.g. barium or calcium salts. Alternatively R and R may represent hydrogen provided there is at least one group R R R R R or R which is anionic.

Compounds within this class are disclosed in US. Pat- 3 ent 2,778,827, inter alia, to which reference may be had, if desired.

As water-soluble polymers suitable for use according to the present invention are mentioned polyvinyl pyrrolidone, polyvinyl-Z-oxazolidone and the copolymer of vinyl pyrrolidone and vinyl acetate having preferably a ratio of vinyl pyrrolidone to vinyl acetate units of at least 60:40. When polyvinyl alcohol is used as the water-soluble polymer of this invention, the results obtained are substantially less satisfactory than with the polymers just mentioned.

The fluorescent compound and the water-soluble polymer may be applied to or incorporated in paper itself, and/or baryta layer, a protective layer or some other auxiliary layer which may be present; in the case of a lightsensitive material, the said fluorescent and polymer components may be added to the silver halide emulsion layer itself, or to any auxiliary layer if desired. The said components may, of course, be added to a substance or substances before forming a layer therefrom, e.'g. they may be added to a constituent or constituents of one or more layers of a photographic material. We would emphasize that it is not essential for the fluorescent compounds and the polymer to be present in one and the same layer. They may be added to or incorporated in different waterpermeable layers. It is even possible to incorporate this polymer into the photographic material or to apply it thereon as a coating and to add the fluorescent compound to a processing bath such as a developing bath, a stop bath and/ or a fixing bath. We found that when a photographic paper was prepared with the fluorescent compound and the polymer in different water-permeable layers and the fluorescent compound diffused out of its layer during a rinsing step, it diffused into the layer containing the polymer and became bound by the polymer to a kind of diffusion-fast addition compound.

Favorable results as to enhancing the optical brightening activity of the fluorescent compound can be attained with vinyl polymers with a molecular weight from 5,000 until 450,000; the best results, however, are attained with water-soluble vinyl polymers having a molecular weight between 50,000 and 250,000.

In general, suitable amounts of vinyl polymer are between 0.1 g. and 4 g. per sq. m. of paper. The amount of fluorescent compound added may in general be between 2 mg. and 500 mg. per sq. m.

The amount of gelatin in a conventional paper emulsion is approximately g. per sq. m.

If the photographic materials are of the type to be wet processed, the bleeding out of the brightening agent should be prevented during the several processing steps such as the treatment in a developing, bleaching, fixing and rinsing bath. In the case the brightening agent is incorporated in a non-hardened hydrophilic colloid layer of a photographic material, or a layer of a photo-graphic material containing a certain amount of hydrophilic colloid as binding agent such as e.g. a baryta-coated layer, bleeding out of the brightening agent from such a layer during wet processing can be practically prevented by using in conjunction with the colloid, one of the above described vinyl polymers having a molecular weight not lower than about 100,000.

In the case bleeding out of the brightening agent is to be prevented from a conventionally hardened layer of a photographic material to be wet processed, which layer consists of or contains a hydrophilic colloid, the molecular weight of the vinyl polymer'does not have to be so high. In conventionally hardened photographic colloid layers said vinyl polymers preferably have a molecular weight not lower than a molecular weight of about 5,000, which molecular Weight is not too low for the results aimed at.

I By way of illustration we may mention that a suitable hardening of gelatin is attained by treating it with 0.5%

of formaldehyde or by treating it with from 0.3 to 6% of aluminum or chrome alum.

The hardening agent need not necessarily be added to the emulsion composition, when strong hardening is necessary a sudden gelling of the emulsion or too high an in crease of the viscosity of the coating composition is prevented preferably by treating the coated layer with a hardening solution (imbibition) or by a hardening realized by diffusion of hardening agent from an adjacent layer (e.g. a baryta layer) or even support such as a paper support to the emulsion layer.

In addition to formaldehyde and the above-mentioned alums, the following hardening agents for gelatin are also suited: dihydroxymethyl urea, glyoxal, monomethyl dimethyl hydantoin and some melamine-formaldehyde resins.

For more details about hardening a photographic coating and about hardening agents we refer more particularly to P. Glafkides, Photographic Chemistry, vol. I, pp. 382383, Fountain Press, London.

The amount of above-mentioned vinyl polymers incorporated into the hardened or unhardened gelatin-containing layers of a photographic material which has to be wet processed and wherein the bleeding out of the brightening agent is practically completely prevented may vary from 1 to 75% by weight relative to the amount of gelatin dependent on the kind of layer. Thus on the one hand gelatin-containing emulsion layers preferably do not contain more than 30% by weight of said vinyl polymers in respect of the amount of gelatin and on the other hand baryta-coated layers may contain up to 75 (preferably 10 to 75%) by weight of said vinyl polymers in respect of the amount of gelatin.

If the photographic materials are not to be wet processed such as e.g. photographic materials containing a print-out emulsion or electrophotographic materials used in xerography the problem of bleeding out of the brightening agent does not exist so that neither the molecular weight of the vinyl polymers nor the ratio of hydro-' philic colloid to the vinyl polymers nor the hardening degree of the colloid layers containing the said polymers and brightening agents are of great importance.

The following general statements indicate certain effects which can be realized by applying the invention.

(1) For a given concentration of the fluorescent compound a netto brightness increase is obtained under the influence of the addition compound formed with the watersoluble polymer.

(2) The maximum quantity of fluorescent compound which can be usefully employed and consequently the degree of whiteness of photographic or other paper which is attainable is increased. If the fluorescent compound is employed alone a loss of fluorescence quickly sets in with concentrations of the fluorescent compound above a certain value due to conglorneration of the fluorescent substance. In case of the addition compound mentioned, this occurs only at higher concentrations of the fluorescent substance.

(3) In consequence of the formation of a kind of addition compound when the fluorescent compound and polymer compound are present either together or separately in the support or one or more of the baryta, emulsion, protective or other layers of a photographic material, the surface color of the material in general undergoes little or no loss due to diffusion of fluorescent product during the treatment and/or protracted rinsing. Indeed, if the average molecular weight of the water-soluble polymer, is sufficiently high (more than 100,000) for inhibiting the diffusion thereof from the layer or layers of the photographic material to which it is added, or if in combination with vinyl polymers with a molecular weight not lower than of about 5000 conventionally hardened gelatin layers are used, the strong affinity of the vinyl polymer for the respective fluorescent compounds will ensure that during the treatment and the rinsing steps these compounds are not washed out in such away that a loss of brightness arises, as it does it fluorescent compounds are used alone.

(4) It is known that the substantivity of the known fluorescent compounds for cellulose is so high that, if a photographic paper, the emulsion or the baryta layer of which contains such a fluorescent compound, is subjected to bath treatment simultaneously with paper containing no or less brightening agent, this fluorescent compound is adsorbed by the latter paper. When a Water-soluble vinyl polymer, as described above, is also present in the first mentioned photographic paper, no transfer of the fluorescent material occurs to the paper containing no or less brightening agent.

A photographic material optically brightened according to the invention may contain color couplers, developing substances, surface-active compounds, sensitizers, antifogging agents, stabilizers, hardening agents, and plasticizers which can be worked up in known way in the photographic material.

The method of optically brightening according to the present invention can be applied to all kinds of paper material and photographic material to be viewed by reflection such as for instance wall-paper, photographic positive paper for black-and-white and color photography for amateur and professional as well as graphic purposes, and positive paper used in the silver complex diffusion transfer process.

The following examples illustrate the present invention Without limiting, however, the scope thereof in any way.

' EXAMPLE 1 A strip A of photographic paper is coated with a baryta layer of the following composition:

Aqueous barium sulphate suspension, 50% kg 2 Aqueous gelatin solution, ccs 1000 4,4'-bis(2-hydroxy 4 phenylamino 1,3,5 triazinyl-6) diaminostilbene 2,2 disodium sulphonate g 4.5

Monomethyl-p-aminophenol sulphate g 1.5 Sodium sulphite (anhydrous) g 25 Hydroquinone g 6 Sodium carbonate (anhydrous) g 40 Potassium bromide g 1 Water to 1000 ccs.

The strips are rinsed for seconds, fixed for 10 minutes and finally rinsed for 3 hours in current water at 15 C. The surface whiteness of the strip B is more strongly brightened than that of strip A.

EXAMPLE 2 Two strips A and B of photographic paper are coated with a baryta layer of the following composition:

Aqueous barium sulphate suspension, 50% kg 2 Aqueous gelatin solution, 10% ccs 1000 4,4-bis(2 hydroxy 4 phenylamino 1,3,5 triazinyl-6) diaminostilbene 2,2 disodium sulphonate g 3.5

The baryta-coated strip A is coated with a conventionally formalin hardened silver bromo-chloride emulsion, the coating composition of which contains 94 g. per kg. of gelatin. The baryta-coated strip B is coated with the same silver bromo-chloride emulsion, to which, however, per kg. of emulsion g. of polyvinyl pyrrolidone are added. After drying these two strips and exposure, they are developed and fixed as in Example 1. The surface 6 whiteness of strip B is more strongly brightened than that of strip A.

EXAMPLE g3 A strip A of baryta-coated photographic paper is coated with a silver chloride paper emulsion formalin hardened in a known way, containing g. of gelatin and 1 g. of 4,4-bis(2-hydroxy-4-phenylamino-1,3,5-triazinyl 6) diaminostilbene-2,2-disodium sulphonate per kg. of emulsion. A strip B of baryta-coated photographic paper is coated with the same silver chloride emulsion to which, however, per kg. of emulsion ccs. of an aqueous solution containing 10 g. of polyvinyl-Z-oxazolidone are added. After drying these two strips and exposure they are developed and fixed as in Example 1. The surface whiteness of the strip B is higher than that of strip A.

EXAMPLE 4 A strip A of photographic paper is coated with a baryta layer of the following composition:

Aqueous barium sulphate suspension, 50% kg 2 Aqueous gelatin solution, 10% ccs 1000 4,4 bis(2,4-dimethoxypropylamino-1,3,S-triazinyl- 6)-diaminostilbene-2,2'-disulphonic acid g 3.9

A strip B of the same paper quality is coated with the same baryta composition to which, however, per kg. of baryta composition 33 g. of polyvinyl pyrrolidone were added. Both baryta-coated strips are coated with a silver bromo-iodide paper emulsion the coating composition of which contains per kg. 100 g. of gelatin and 1.6 g. of chrome alum. After drying these two strips and exposure they are developed and fixed as in Example 1. The sur face whiteness of the strip B is more strongly brightened than that of strip A.

EXAMPLE 5 A strip A of photographic paper is coated with a baryta layer of the following composition:

Aqueous barium sulphate suspension, 50% kg 2 Aqueous gelatin solution, 10% ccs 1000 4,4 bis[2,4-di(4-phenyl)-anilino-l,3,5-triaZinyl-6]- diaminostilbene-Z,2-disulphonic acid g 4 A strip B of the same paper quality is coated with the same baryta composition to which, however, per kg. of baryta composition 36.5 g. of polyvinyl pyrrolidone were added. Both baryta-coated strips are coated with a silver bromo-iodide paper emulsion. strips and exposure, they are developed and fixed as in Example 1. The surface whiteness of the strip B is more strongly brightened than that of strip A.

EXAMPLE 6 As in Example 4, but instead of 3.5 g. of 4,4'-bis(2- hydroxy 4 phenylamino-1,3,5-triazinyl-6)-diamino-stilbenc-2,2-disodium sulphonate are used 3.75 g. of 4,4'-bis [2 amino 4-(beta hydroxyethylamino)-1,3,5-triazinyl- 6] -diaminostilbene-2,2-disodium sulphonate.

EXAMPLE 7 A strip A of baryta-coated photographic paper is coated with a silver bromide paper emulsion which per kg. of emulsion contains 1 g. of 4,4-bis(4-phenylcarbamyl)-diiaminostilbene-2,2-disodium sulphonate and 75 g. of gelatin. The said emulsion is formalin hardened in a known way. A strip B of baryta-coated photographic paper is coated with the same silver bromide emulsion to which, however, per kg. of emulsion 100 ccs. of an aqueous solution containing 10 g. of polyvinyl pyrrolidone were added. After drying these two strips and exposure, they are developed and fixed such as in Example 1. The whiteness of the surface color of the strip B thus treated is not lost on rinsing and strip B yields after complete finish a photographic image wherein the light parts are more strongly brightened as compared to the whiteness of strip A.

After drying these two 7 EXAMPLE 8 As in Example 7, but instead of 1 g. of 4,4-bis(4- phenylc-arbamyl)-di'aminostilbene-2,2-disodium sulphonate l g. of 4,4'-bis(4-furoylamino)-diarninostilbene-2,2'- disulphonic acid is added to the emulsion.

EXAMPLE 9 A strip A of baryta-coated photographic paper is coated with a silver bromo-iodide paper emulsion formalin hardened in a known way which per kg. of emulsion contains 1 g. of 4,4-bis(2-hydroxy-4-phenylamino-l,3,5-triazinyl- 6)-diaminostilbene-2,Zdisodium sulphonate and 130 g. of gelatin. A strip B of baryta-coated photographic paper is coated with the same silver bromo-iodide emulsion to which, however, per kg. of emulsion 10 g. of a copolymer 40:60 of vinylacetate and N-vinyl pyrrolidone of molecular weight of about 50,000 were added. After drying these two strips and exposure, they are developed and fixed as in Example 1. The surface whiteness of the strip B is more strongly brightened than that of strip A.

EXAMPLE 10 On a paper support A is coated a layer composed of a suspension of 280 g. of barium sulphate in 1500 ccs. of a 2% aqueous gelatin solution to which 0.6 g. of 4,4'-bis (2 hydroxy 4-phenylamino-1,3,5-triaZinyl-6)-diaminostilbene-2,2-disodium sulphonate in 30 cos. of water has been added. Thereupon an unhardened precipitating layer is coated consisting of an aqueous gelatin solution containing colloidal silver sulphide nuclei. This material, according to the method described in Belgian Patent 441,852 is brought into contact with a negative silver halide emulsion layer which has previously been exposed to actinic light. During processing in the developing bath the non-exposed silver halide diffuses from the negative material into the positive receiving layer and produces a positive image on the receptive layer on paper support A. On a paper support B a layer is coated having the same composition as the baryta layer coated on paper support A to which, however, 6 g. of polyvinyl pyrrolidone in 30 ccs. of water have been added. Exactly as for paper support A the paper support B is coated with a precipitating layer comprising silver sulphide nuclei. When paper B is processed in exactly the same circumstances as the diffusion-transfer positive material A a more strongly brightened surface whiteness is obtained for paper B.

EXAMPLE 11 On a strip A of a photographic paper, provided with a baryta layer, a silver bromide paper emulsion formalin hardened in a known Way and containing 75 g. of gelatin per kg. is coated. A strip B of a photographic material provided with a baryta layer is coated with the same silver bromide emulsion to which, however, 100 ccs. of an aqueous solution containing 20 g. of polyvinyl pyrrolidone per kg. of emulsion are added. After drying the two strips and exposure, they are developed and fixed as in Example 1 with the exception that 0.5 g. of 4,4-bis(2- hydroxy 4 phenylarnino-1,3,5-triazinyl-6)-di-aminostilbene-2,2'-disodium sulphonate per liter has previously been added to the developing bath. The surface whiteness of strip B is more strongly brightened than that of strip A.

EXAMPLE 12 Two strips A and B of photographic paper are coated with a baryta layer of the following composition:

Aqueous barium sulphate suspension, 50% kg 2 Aqueous gelatin solution, 10% ccs 1000 4,4'-bis(2-hydroxy-4-phenylamino 1,3,5-triazinyl- 6)-diaminostilbene-2,2-disodium sulfonate g 3.5

The baryta-coated strip A is coated with a silver bromide paper emulsion the coating composition of which contains per kg. 100 g. of gelatin and 0.8 g. of formaldehyde. The emulsion is coated so that 1 kg. covers 10 sq. m.

The baryta-coated strip B is coated with the same silver bromide paper emulsion, to which, however, per kg. of emulsion 20 g. of polyvinyl pyrrolidone (average molecular weight: 50,000) are added. After drying these two strips are exposed to white light and developed at 20 C. for 1.5 min. in a developing bath of the following composition:

G. Monomethyl-p-aminophenol sulfate 1.5 Sodium sulfite (anhydrous) 25 Hydroquinone 6 Sodium carbonate (anhydrous) 40 Potassium bromide 1 Water up to 1000 ccs.

The strips are treated for 5 sec. in a stop-bath of the following composition:

Ccs.

Water 1000 Acetic acid (28%) 50 Thereupon the strips are fixed for 30 min. in an acid fixing bath of the following composition:

G. Sodium thi-osulfate-S, water 200 Potassium metabisulfite 25 Water up to 1000 ccs.

Table Relative reflection Strip Relative reflection value after rinsing for value after processing 6 hours water of EXAMPLE 13 A strip A of baryta-coated photographic paper is coated pro rata of 1 kg. per 8 sq. m. with a silver chloride paper emulsion containing per kg. of emulsion 1 g. of 4,4'-bis(2- hydroxy-4-phenylamino-1,3,5-triazinyl 6) diaminostilbene-2,2'-disodium sulfonate, 80 g. of gelatin and mg. of formaldehyde. A strip B of baryta-coated photographic paper is coated with the same silver chloride paper emulsion to which, however, per kg. of emulsion 100 ccs. of an aqueous solution containing 10 g. of polyvinyl-2- oxazolidione (average molecular weight: 30,000) are add ed. After drying and exposure, these two strips are processed as described in Example 12.

The relative reflection values are measured as described in Example 12 and listed in the following table.

Table Relative reflection value after rinsing for 6 hours with water of Relative reflection Strip value after processing 9 EXAMPLE 14 A strip A of baryta-coated photographic paper is coated pro rata of 1 kg. per sq. m. with a silver bromide paper emulsion which contains per kg. of emulsion l g. of 4,4'- bis(4-phenylcarbamyl)-diaminostilbene-2,2-disodium sulfonate, 100 g. of gelatin and 120 mg. of formaldehyde. A strip B of baryta-coated photographic paper is coated With' the same silver bromide paper emulsion to which, however, per kg. of emulsion 100 ccs. of an aqueous solution containing 10 g. of polyvinyl pyrrolidone (average molecular weight: 18,000) were added. After drying and exposure to white light, these two strips are developed and fixed as described in Example 12.

The relative reflection values are measured as described 1. A photographic material comprising a support bearing a layer of a baryta coating containing gelatin as the essential binding agent and at least one gelatin silver halide emulsion layer containing gelatin as the essential binding agent, said material being characterized in that at least one of said layers has homogeneously distributed through the gelatin thereof an anionic water-soluble 4,4'- diaminostilbene fluorescent compound adapted for optically brightening said material, said fluorescent compound being incorporated in said gelatin in the dissolved state and one of said layers has homogeneously distributed throughout the gelatin thereof a Water-soluble vinyl polymer selected from the .group consisting of polyvinyl pyrrolidone, polyvinyl-Z-oxazolidone, and a vinyl pyrrolidone-vinyl acetate copolymer, said polymer being incorporated .in said gelatin in the dissolved state whereby the brightness of said material is enhanced.

2. The material of claim 1 wherein the same layer contains both said fluorescent compound and said vinyl polymer.

3. The material of claim 1 wherein one of said layers contains said fluorescent compound and another contains said vinyl polymer.

4. The method of enhancing the brightness of a photographic light-sensitive material comprising a support, a layer of a baryta-coating containing gelatin as the essential binding agent and a gelatin silver halide emulsion layer containing gelatin as the essential binding agent, wherein at least one of said layers has homogeneously distributed throughout the gelatin thereof an anionic water-soluble 4,4-diaminostilbene fluorescent compound for brightening said material, said fluorescent compound being incorporated in said gelatin in the dissolved state, said method being characterized by the step of incorporating into one of said layers a water-soluble vinyl polymer selected from the group consisting of polyvinyl pyrrolidone, polyvinyl-Z-oxazolidone, and a vinyl pyrrolidone-vinyl acetate copolymer, said polymer being incoporated in the dissolved state,

5. The method of claim 4 wherein said vinyl polymer is incorporated in said baryta layer, which layer also contains said fluorescent compound.

6. An improved method of brightening an image-receiving material bearing a precipitating layer containing gelatin as the essential binding agent, which comprises incorporating into said layer a water-soluble vinyl polymer selected from the group consisting of polyvinyl pyrrolidone, polyvinyl-Z-oxazolidone, and a vinyl pyrrolidone-vinyl acetate copolymer and an anionic water-soluble 4,4-diarninostilbene fluorescent compound for brightening said material, both said vinyl polymer and said fluorescent compound being incorporated into said layer in the dissolved state.

7. An improved method of brightening a photographic non-light-sensitive image-receiving material bearing a layer containing gelatin as the essential binding agent, which comprises incorporating into said layer a watersoluble vinyl polymer selected from the group consisting of polyvinyl pyrrolidone, polyvinyl-Z-oxazolidone, and a vinyl pyrrolidone-vinyl acetate copolymer and an anionic diaminostilbene fluorescent compound for brightening said material, both said vinyl in said fluorescent compound being incorporated in the dissolved state.

8. A method of brightening a photographic material bearing a layer containing gelatin as the essential binding agent and having homogeneously distributed through out the gelatin in said layer a Water-soluble vinyl polymer selected from the group consisting of polyvinyl pyrrolidone, polyvinyl-Z-oxazolidone, and a vinyl pyrrolidone-vinyl acetate copolymer, said vinyl polymer being incorporated in said gelatin in the dissolved state, which comprises the step of treating said material with an aqueous bath containing an anionic water-soluble 4,4- diaminostilbene fluorescent compound for brightening the same.

9. A photographic material bearing a surface layer containing gelatin as the essential binding agent, said layer having homogeneously distributed throughout the gelatin thereof an addition compound of a water-soluble vinyl resin selected from the group consisting of polyvinyl pyrrolidone, polyvinyl-Z-oxazolidone, and a vinyl pyrrolidone-vinyl acetate copolymer, and an anionic water-soluble 4,4'-diaminostilbene fluorescent compound for brightening said material obtained by contacting said vinyl resin and said fluorescent compound in the dissolved state.

10. A photographic material containing a conventionally hardened gelatin-containing emulsion layer wherein said gelatin is the essential binding agent thereof, said layer having homogeneously distributed throughout the .gelatin thereof an addition compound of a Water-soluble vinyl resin selected from the group consisting of a watersoluble vinyl resin selected from the group consisting of polyvinyl pyrrolidone, polyvinyl-Z-oxazolidone, and a vinyl pyrrolidone-vinyl acetate copolymer, and an anionic Water-soluble 4,4-diaminostilbene fluorescent compound for brightening said material obtained by contacting said vinyl resin and said fluorescent compound in the dissolved state, the ratio of vinyl resin to gelatin ranging from 1 to 30% by Weight.

11. A photographic material containing a baryta coating which contains gelatin as the essential binding agent thereof, said coating having homogeneously distributed throughout the gelatin thereof an addition compound of a water-soluble vinyl resin selected from the group con sisting of a water-soluble vinyl resin selected from the group consisting of polyvinyl pyrrolidone, polyvinyl-2- oxazolidone, and a vinyl pyrrolidone-vinyl acetate copolymer, and an anionic water-soluble 4,4'-diaminostilbene fluorescent compound for brightening said material obtained by contacting said vinyl resin and said fluorescent compound in the dissolved state, the ratio of vinyl resin to gelatin in the baryta coating ranging from 10 to by weight.

12. A photographic material comprising a gelatin-containing layer wherein said gelatin is the essential binding agent of said layer, said layer having homogeneously distributed throughout the gelatin thereof an addition compound of a water-soluble vinyl resin selected from the group consisting of polyvinyl pyrrolidone, polyvinyl- 2-oxazolidone and a vinyl pyrrolidone-vinyl acetate copolymer, and an anionic Water-soluble 4,4'- diaminostilbene fluorescent compound for brightening said material 1 1 obtained by contacting said vinyl resin and said fluorescent compound in the dissolved state, said vinyl resin having a molecular Weight of at least 100,000, the ratio of vinyl resin to gelatin in the said layer ranging from 1 to 75% by weight.

13, The material of claim 1 wherein said fluorescent compound is selected from the group consisting of bis- N-acyl and bis-N-triazinyl derivatives of 4,4-diaminostilbene.

14. The method of claim 4 wherein said fluorescent compound is selected from the group consisting of his- N-acyl and bis-N-triazinyl derivatives of 4,4-diaminostilbene.

15. The method of claim 7 wherein said fluorescent compound is selected from the group consisting of bis- N-acyl and bis-N-triazinyl derivatives of 4,4-diaminostilbene.

16. The method of claim 8 wherein said fluorescent compound is selected from the group consisting of his- N-acyl and bis-N-triazinyl derivatives of 4,4'-diaminostilbene.

17. The material of claim 9 wherein said fluorescent compound is selected finom Ithe group consisting of his- N-acyl and 'bis-N-triazinyl derivatives of 4,4'-diaminostilbene.

References Cited by the Examiner UNITED STATES PATENTS 2,875,052 2/1959 Wayde 96-114 2,887,379 5/1959 Blake et a1. 96-82 3,047,390 7/1962 Koerber et al 9682 FOREIGN PATENTS 588,529 3/1960 Belgium,

590,935 11/1960 Belgium.

956,558 1/1957 Germany.

672,803 5/ 1952 Great Britain.

817,617 8/1959 Great Britain.

867,899 5/1961 Great Britain.

OTHER REFERENCES Tsubomura et al.: Chem. Abstracts, vol. 53, No. 9, May 10, 1959, page 8107d (abstract of Bunko Kenkyu 6, No. 3, 10-14 (1957)).

NORMAN G. TORCHIN, Primary Examiner,

A. LIBERMAN, D. PRICE, Assistant Examiners. 

1. A PHOTOGRAPHIC MATERIAL COMPRISING A SUPPORT BEARING A LAYER OF BARYTA COATING CONTAINING GELATIN AS THE ESSENTIAL BINDING AGENT AND AT LEAST ONE GELATIN SILVER HALIDE EMULSION LAYER CONTAINING GELATIN AS THE ESSENTIAL BINDING AGENT, SAID MATERIAL BEING CHARACTERIZED IN THAT AT LEAST ONE OF SAID LAYERS HAS HOMOGENEOUSLY DISTRIBUTED THROUGH THE GELATIN THEREOF AN ANIONIC WATER-SOLUBLE 4,4''DIMINOSTILBENE FLUORESCENT COMPOUND ADAPTED FOR OPTICALLY BRIGHTENING SAID MATERIAL, SAID FLUORESCENT COMPOUND BEING INCORPORATED IN SAID GELATIN IN THE DISSOLVED STATE AND ONE OF SAID LAYERS HAS HOMOGENUOUSLY DISTRIBUTED THROUGHOUT THE GELATIN THEREOF A WATER-SOLUBLE VINYL POLYMER SELECTED FROM THE GROUP CONSISTING OF POLYVINYL PYRROLIDONE, POLYVINYL-2-OXAZOLIDONE, AND A VINYL PYRROLIDONE-VINYL ACETATE COPOLYMER, SAID POLYMER BEING INCORPORATED IN SAID GELATIN IN THE DISSOLVED STATE WHEREBY THE BRIGHTNESS OF SAID MATERIAL IS ENHANCED. 